The operation of internal combustion engines in frigid environments brings many problems resulting from the low temperatures, among which are:
providing a safe and comfortable working environment for the engine operator; PA1 separating moisture from the motor fuel; PA1 obtaining an optimum mixture of fuel and air before inducting said mixture into the engine; and PA1 preventing heat loss during the foregoing operations. PA1 water absorbed or entrained in fuel can freeze, endangering the integrity of enclosures and lines; PA1 evaporation of either liquid reduces the temperature of the mixture, increasing the danger of icing; PA1 the space for accomodating insulation or for housing separator equipment is relatively limited; PA1 the problem of maintenance and repair is very great, since the environment of use is severe, in terms of vibration, extremes of temperature, etc.; PA1 the users/operators, of vehicles especially, are often mechanically and technically unsophisticated, requiring the equipment thereof to be troublefree and easy to maintain; and PA1 the proportion of overall equipment weight and cost to be allocated to heating and separator functions is usually small, since they do not represent major, or even subsidiary, engine or vehicle objectives. PA1 fuel vaporizes more easily if heated; PA1 warmed vaporized fuel mixes more thoroughly with air, thus more easily achieving an optimum fuel/air mixture. PA1 heating an engine operator enclosure (i.e., a cab); PA1 heating fuel for the engine; PA1 maintaining a desirable level of heat for each purpose under varying demands; PA1 separating entrained moisture from fuel; and PA1 reducing heat loss to the minimum during each of the foregoing operations. The system is especially effective in extremely cold climates, where operator comfort has sometimes been slighted for engine operating efficiency, and where moisture-containing fuels can cause several different and undesirable problems. PA1 1. processes for heating the operator space and for heating the engine fuel are inter-related in a novel way, with the first overriding the second in certain extreme conditions; PA1 2. a surface treatment of the fuel heater/moisture separator cannister for improving the heating of the fuel significantly conserves heat energy for the operator enclosure; PA1 3. the "roughened or scabrous surface" of Kay, which is therein claimed to effect a significant improvement in the separation of absorbed and entrained moisture from fuel, is exploited in a novel way to obtain unexpected improvements in: PA1 4. a further novel treatment of the physical form of separator baffle plates further increases the efficiency of heating the fuel; PA1 as will hereinafter be explained in greater detail. PA1 1. the system of the present invention circulates heating fluid (normally coolant from the engine) and directs it through a flow diverter, which directs a thermostatically controlled adjustable proportion of the heating fluid through the cab heater as needed to maintain a safe and comfortable working environment for the operator, and the balance is diverted through the fuel heater/separator, where it warms the fuel; PA1 2. the fuel heater/separator of the present invention includes: PA1 a. a baffle plate which has: PA1 b. the bottom portion of the cannister is formed of an inner and outer shell, forming a closed space therebetween for heating fluid to circulate therethrough, heating the inner shell and consequently the fuel in contact therewith; and PA1 c. the angle between said inner and outer shells of said cannister is limited to an angle between 0.degree.; PA1 d. the outer surface of said cannister is polished to reduce heat loss therefrom. PA1 1. a system for both space heating and fuel heating, using heated engine coolant therefor, automatically apportioning said coolant to each use in accordance with predetermined requirements therefor; PA1 2. a combination fuel separator and heater of increased efficiency and simplicity, providing:
A safe and comfortable working environment for vehicle operators, even in frigid environments, is not normally associated with the heating of fuels and fuel/air mixtures, or the demoisturizing of fuels. However, since heat is a common factor in each function, they are considered as relevant and interrelated aspects of the same problem in the present invention.
Separating moisture from fuel is important in frigid conditions. Several problems become critical, especially for engines used in motor vehicles:
It is well known that heating fuel and fuel/air mixtures for use in internal combustion engines becomes critical as the environmental temperature becomes colder, because the more volatile fuels, such as gasoline or even kerosene, have a substantial cooling effect as they vaporize, causing problems with vaporization and icing. Extremely cold weather intensifies these problems. Several devices have been developed to heat fuel/air mixtures for such engines, but these ignore the fact that fuel, if it is heated, vaporizes more easily and mixes with air more efficiently. Diesel fuel, on the other hand, often needs to be heated to enable it to vaporize and mix properly with air to obtain an optimally combustible mixture. Especially is this true in extremely cold climates.
Thus, solutions to these problems for engines using more volatile fuels often are not satisfactory for diesel engines.
The heating of the operator's space, the heating of fuel, and the separation of moisture absorbed and entrained therein, traditionally have been dealt with as separate problems, and the following prior art survey will follow that pattern, although the present invention solves them as part of the same problem.
Space heaters for motor vehicles are familiar to everyone, and little needs to be said about those that use radiator coolant as the heat source.
Fuel heaters for diesel fuel are used widely. Baker U.S. Pat. No. 4,372,260 discloses an engine heater attachment for heating the fuel of an engine before introducing it into the combustion chambers. This obtains better vaporization of the fuel, with subsequent easier ignition of the fuel/air mixtuure, and reduces any tendency of the fuel lines and small openings in the fuel system to clog with ice or congealed fuel components which are often encountered in some of the extremely cold climates in which engines are required to operate.
Heaters for fuel/air mixtures are common in the prior art. However, in frigid environments, these are less than satisfactory, as:
Gagnon U.S. Pat. No. 4,399,794 discloses a carburetion system for an internal combusion engine which seeks to combine more complete vaporization of a fuel/air mixture with heating thereof. Drops of fuel are dropped onto a rotating fan, breaking them into smaller droplets, aiding in their vaporization, and helping to achieve a more complete fuel/air mixture thereby. Before this mixture goes into the manifold for distribution to the cylinders, it is drawn through a heater for heating and better vaporization and mixing. Other than disclosing a combination of the two functions, there is little relationship to the present invention, than which it is substantially less efficient.
Baker is substantially more efficient than the Gagnon disclosure, as heating fuel before vaporization makes it easier to vaporize and obtain an optimum mixture with air.
The problem of separating water from fuel is one aspect of the problem of separating one liquid from another, and it is intensified in frigid conditions. This has been the subject of a number of patents, of which Kay U.S. Pat. No. 3,362,534 is the most pertinent.
Kay discloses an improved apparatus for separating entrained moisture from liquid fuels, wherein the fuel is passed, in laminar flow, over a roughened baffle plate. The roughened surface serves to trap droplets of moisture by surface tension, and they are drawn away by gravity against the flow of the fuel. According to the disclosure, the surface roughness must be within the limits of 100-180 RMS (millionths of an inch) for greatest efficiency.
According to Kay, this improvement is substantially more efficient in separating moisture from fuel than previous methods.
Both Kay and Baker disclose features which are incorporated into the present invention but which, separately or together, do not anticipate or even suggest the present invention.